Casing Centralizer Coupling

ABSTRACT

A well casing centralizer coupling is provided. The casing centralizer coupling is constructed to be suitable for coupling well casing for use in drilling with casing operations. The casing centralizer coupling includes a body having a number of centralizing blades arranged radially around an exterior surface of the body for contacting an inner surface of a well bore to centralize the well casing. Each centralizing blade includes a transverse profile that results in the blade having a reduced contact with the well bore and includes a hard faced contact surface. A method of constructing the well casing centralizer coupling to have a number of centralizing blades with such a transverse profile and a hard faced surface is also provided.

FIELD OF THE INVENTION

The present invention relates generally to well casing couplings and well casing centralizers. More particularly, relating to a combined well casing coupling and centralizer that is suitable for use in drilling with casing operations.

DESCRIPTION OF RELATED ART

In a standard operation of drilling and completing an oil well multiple steps are performed through the process. First, a bore hole of a desired diameter and depth is drilled into a formation using a drill bit and a drill string comprising of coiled tubing or multiple sections of rigid drilling pipe coupled together. Once the bore hole has been drilled, the drill string is removed from the bore hole and a casing string is inserted. The casing string includes multiple sections of pipe connected end-to-end by threaded couplings. Centralizing devices are attached along the length of the casing at regular intervals to center the casing within the bore hole so when the casing is cemented in the bore hole the cement is evenly distributed around the casing. Most of these centralizers have an outside diameter (OD) equal to or smaller than the bore hole interior diameter (ID). Others yet can have a greater OD and include spring loaded mechanisms that compress to conform to the bore hole ID.

Many types of centralizers have been used in the industry and the centralizers range from devices that are attached to the casing by a friction system, are bolted on, are positioned around the casing between the casing couplings or are formed as part of a casing coupling.

Examples of casing centralizers can be found in U.S. Pat. Nos. 6,464,013; 5,575,333; 4,595,058; 3,762,472; 2,309,791 and 1,807,050.

Recently, new developments have been made in the art of drilling and completing a well which remove the step of using a separate drill string and casing string to complete a well. In the drilling of shallow to medium depth formations advancements have been made that allow the use of the casing string as the drill string, thereby eliminating the need of using a separate drill string, this operation is typically termed “drilling with casing”.

While the need to use a separate drill string is eliminated in drilling with casing, the casing must still be centralized in order to be properly cemented. The prior art centralizers are not capable of standing up to the force and abuse to which they are subjected during a drilling operation. As such, the present invention provides a centralizer that withstands the force and abuse during the drilling operation while maintaining a highly regulated specification for use, which is not attainable by prior art centralizers.

SUMMARY OF THE INVENTION

In accordance with the present invention, a casing centralizer coupling which meets strict American Petroleum Institute (API) specifications and is capable of use in drilling with casing operations is provided.

In general, in one aspect, a casing centralizer coupling is provided. The coupling includes a body having a threaded first end, a threaded second end, a through bore extending from said first end to said second end, and an exterior surface. A plurality of centralizing blades projecting outwardly and extending along a length of the exterior surface. And each of the plurality of centralizing blades defining an outwardly facing surface having an arcuately shaped transverse cross section

In general, in another aspect, a casing centralizer coupling is provided. The coupling includes a body having a threaded first end, a threaded second end, a through bore extending from said first end to said second end, and an exterior surface. A plurality of centralizing blades projecting outwardly and extending along a length of the exterior surface. Each of the plurality of centralizing blades defining an outwardly facing surface having an arcuately shaped transverse cross section and opposed outwardly beveled transverse edges and opposed outwardly beveled longitudinal edges.

In general, in another aspect, a casing centralizer coupling is provided. The coupling includes a body having a threaded first end, a threaded second end, a through bore extending from said first end to said second end, and an exterior surface. A plurality of centralizing blades projecting outwardly and extending along a length of the exterior surface. Each of the plurality of centralizing blades defining an outwardly facing surface having an arcuately shaped transverse cross section and opposed outwardly beveled transverse edges and opposed outwardly beveled longitudinal edges. And at least a portion of each of the plurality of centralizing blades are hard faced.

In general, in another aspect, a combined casing coupling and casing centralizer is provided. The combined casing coupling and casing centralizer includes a body having a threaded first end, a threaded second end, a through bore extending from said first end to said second end, and an exterior surface. A plurality of centralizing blades projecting outwardly and extending along a length of the exterior surface. Each of said plurality of centralizing blades defining an outwardly facing surface having an arcuately shaped transverse cross section, opposed outwardly beveled transverse edges, opposed outwardly beveled longitudinal edges, and wherein at least the outwardly facing surface is hard faced.

There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated.

Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of presently preferred, but nonetheless illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a schematic diagram of the casing centralizer coupling positioned within a well bore;

FIG. 2 is a perspective view of the casing centralizer coupling having straight centralizing blades positioned radially around an exterior surface of the coupling;

FIG. 3 is an end view of the casing centralizer coupling;

FIG. 4 is a sectional view of the casing centralizer coupling take along line 4-4 in FIG. 3;

FIG. 5 is a sectional view of the casing centralizer coupling taken along line 5-5 in FIG. 4; and

FIG. 6 is an alternate embodiment of the casing centralizer coupling having swept shaped centralizing blades.

The same reference numerals refer to the same parts throughout the various figures.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and particularly to FIGS. 1-5, a preferred embodiment of the casing centralizer coupling of the present invention is shown and generally designated by the reference numeral 10. The casing centralizer coupling 10 is of a design and construction such that the coupling can withstand the abuse of drilling rotation, thereby making the coupling of the present invention desirable and usable for the coupling of casing for using in drill while casing operations. Prior art centralizers are not designed nor are they robust enough to withstand forces subjected upon the centralizer during drilling rotation.

Now with reference to FIG. 1, a new and improved casing centralizer coupling 10 of the present invention for coupling sections of casing together in drilling while casing operations will be described. More particularly, the casing centralizer 10 is shown in use within a bore hole 100 coupling two sections of casing 102 and 104 together and centralizing the casing within the bore hole.

With reference to FIGS. 2 and 3, the casing centralizer coupling 10 includes a body 12 having opposed threaded ends 14 and 16 and a through-bore 18 extending through the body between ends 14 and 16. While the body 12 is shown with female threaded ends 14 and 16, the body can include male threaded ends or a male threaded end and a female threaded end depending upon the casing in which the casing centralizer coupling is to be used. Additionally, the threaded ends can include torque shoulders 15 that are commonly used in threaded casing couplings to resist high tightening torque which can result in damage to the threaded coupling.

The casing centralizer coupling 10 includes a plurality of centralizing blades 20 arranged radially around and project outwardly from an exterior surface 22 of the body 12. Each centralizing blade 20 extends along a length of the exterior surface 22 in a general longitudinal direction. Each centralizing blade 20 includes outwardly beveled transverse edges 24 and 26, outwardly beveled longitudinal edges 28 and 30, and an outwardly facing surface 32 having an arcuately shaped transverse cross section. The outwardly facing surface 32 can be hard faced.

As can be seen in FIG. 3, each centralizing blade 20 includes a transverse profile that results in the blade having a reduced contact with the well bore. The reduced contact with the well bore is such that during rotation of the casing centralizer coupling 10 along with the casing string 106 the centralizing blades 20 rotate across and against the bore hole with a bruising (glancing impact) not in a digging or direct impact as would occur with a profile including sharp edges. The resulting effect is lower torque requirements for rotation of the casing string during drilling and a high wear resistance of the casing centralizer coupling.

Additionally, the outwardly beveled transverse edges 24 and 26 clearly shown in FIG. 4 provides smooth entrance of each centralizing blade 20 as the blade moves into the bore hole. The smooth entrance of each centralizing blade 20 also reduces rotational torque requirements of the casing string and prevents the centralizing blades 20 from digging into the bore hole and provides increased wear resistance of the casing centralizer coupling 10.

Each centralizing blade 20 having the unique transverse and longitudinal profiles can either be formed integrally with the body 12 for example through integral machining or casting. Preferably, the blades 20 are of a multi-component construction formed onto the body 12 using a specialized process.

With reference to FIGS. 4 and 5, the multi-component construction of a centralizing blade 20 is shown. In this construction, the centralizing blade includes a central core member 40, first and second fillet members 42 and 44 defining the outwardly beveled transverse edges 24 and 26 respectively, third and fourth fillet members 46 and 48 defining the outwardly beveled longitudinal edges 28 and 30 respectively, and a surface member 50 defining the outwardly facing surface 32.

The multi-component centralizing blade is created by a specialized process which results in a casing centralizing collar that meets current American Petroleum Institute (API) Grade specifications. The specialized process includes welding the core member 40 to the exterior surface 22 of the body 12 using a welder, such as a pulse arc GMAW robot welder, thereby making the core member integral with the body. The first, second, third and fourth fillet members 42, 44, 46, 48 are formed by the welder in the process of welding the core member 40 to the body 12. The use of a pulse arc GMAW robot welder eliminates the requirement of preheating the body 12 to reduce deformation caused by heat generated by a standard MIG welder.

The process further includes a step of forming the surface member 50 onto the core member 40 as illustrated. The surface member 50 is formed of a hard face material which is deposited upon the core member 40 using a robot plasma system. The core member 40 acts as a heat sink during this process and absorbs and dissipates a sufficient amount of heat generated during the deposition of the hard face material so that the body 12 is not dimensional distorted. Hard facing is defined as the application of a hard material on the surface of a softer material or substrate. The hard face material of the surface member 50 is of a tungsten hard facing material comprising tungsten in a matrix, such as a chromium nickel (CrNi) matrix. Most preferably, of a tungsten carbide hard facing material comprising tungsten carbide in a matrix, such as chromium nickel (CrNi).

In a test sample, the core member 40 was a flat bar having a dimension of 0.25 inches×0.75 inches and the body was a standard API L casing coupling. However, other casing couplings having API 5B, 5CT and 5C2 specification can also be utilized. It is contemplated that other API standard couplings could reasonably be used. Further, any casing coupling having specifications defined by another system which meet or exceed the API standards could also be used.

The test sample demonstrated a Vickers hardness, tensile strength and bend test results of the HAZ and other critical areas of the casing centralizer coupling meeting API N-80 specifications.

In a further step, the casing centralizer coupler 10 can be H₂S environment certified by post weld heat treating the core member 40 prior to depositing the hard facing material of the surface member onto the core member 40.

With reference to FIG. 6, the casing centralizer coupling 10 is shown having at least one swept centralizing blade 20.

A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims. 

1. A well casing centralizer comprising: a body having a threaded first end, a threaded second end, a through bore extending from said first end to said second end, and an exterior surface; a plurality of centralizing blades projection outwardly and extending along a length of said exterior surface; each of said plurality of centralizing blades defining an outwardly facing surface having an arcuately shaped transverse cross section, opposed outwardly beveled transverse edges and opposed outwardly beveled longitudinal edges; and wherein at least said outwardly facing surface is hard faced.
 2. The well casing centralizer of claim 1, wherein said outwardly facing surface is parallel to said exterior surface.
 3. The well casing centralizer of claim 1, wherein each of said plurality of centralizing blades being integral with said body.
 4. The well casing centralizer of claim 1, wherein each of said plurality of centralizing blades being attached to said body.
 5. The well casing centralizer of claim 4, wherein said opposed outwardly beveled transverse edges and opposed outwardly beveled longitudinal edges being of weld material.
 6. The well casing centralizer of claim 1, wherein said hard facing material is tungsten in a matrix.
 7. The well casing centralizer of claim 1, wherein said hard facing material is tungsten carbide in a matrix.
 8. The well casing centralizer of claim 1, wherein each of said plurality of centralizing blades is swept-shaped.
 9. The well casing centralizer of claim 1, wherein each of said plurality of centralizing blades is helical shaped.
 10. A combined casing coupling and casing centralizer, comprising: a body having a threaded first end, a threaded second end, a through bore extending from said first end to said second end, and an exterior surface; at least one centralizing blade projection outwardly and extending along a length of said exterior surface; and each of said plurality of centralizing blades defining an outwardly facing surface having an arcuately shaped transverse cross section.
 11. The combined casing coupling and casing centralizer of claim 10, wherein each of said at least one centralizing blade comprising: a central body defining said opposed outwardly beveled transverse edges and opposed outwardly beveled longitudinal edges; and wherein said outwardly facing surface being of a hard facing material.
 12. The combined casing coupling and casing centralizer of claim 11, wherein said hard facing material is tungsten in a matrix.
 13. The combined casing coupling and casing centralizer of claim 11, wherein said hard facing material is tungsten carbide in a matrix.
 14. The combined casing coupling and casing centralizer of claim 11, wherein said at least one centralizing blade is selected from the group consisting of a swept blade and a helical blade.
 15. The combined casing coupling and casing centralizer of claim 14, wherein said hard facing material is tungsten in a matrix.
 16. The combined casing coupling and casing centralizer of claim 14, wherein said hard facing material is tungsten carbide in a matrix.
 17. The combined casing coupling and casing centralizer of claim 10, wherein each of said plurality of centralizing blades comprising: a central body; weld material defining said opposed outwardly beveled transverse edges and opposed outwardly beveled longitudinal edges; and wherein said outwardly facing surface being of a hard facing material.
 18. The combined casing coupling and casing centralizer of claim 17, wherein said hard facing material is tungsten in a matrix.
 19. The combined casing coupling and casing centralizer of claim 17, wherein said hard facing material is tungsten carbide in a matrix.
 20. The combined casing coupling and casing centralizer of claim 17, wherein said at least one centralizing blade is selected from the group consisting of a swept blade and a helical blade.
 21. The combined casing coupling and casing centralizer of claim 20, wherein said hard facing material is tungsten in a matrix.
 22. The combined casing coupling and casing centralizer of claim 20, wherein said hard facing material is tungsten carbide in a matrix.
 23. A method of making a combined casing coupling and casing centralizer including the steps of: attaching at least one centralizing blade core to a casing coupling by pulse arc GMAW welding such that opposed outwardly beveled transverse edges and opposed outwardly beveled longitudinal edges are formed along the perimeter of said at least one centralizing blade core; and hard facing an outward facing surface of said at least one centralizing blade core.
 24. The method of making a combined casing coupling and casing centralizer of claim 23, wherein said hard facing of said outward facing surface forms a hard faced surface along the length of said outward facing surface of an arcuately shaped transverse cross section.
 25. The method of making a combined casing coupling and a casing centralizer of claim 24, wherein four centralizing blade cores are attached to said casing coupling.
 26. The method of making a combined casing coupling and a casing centralizer of claim 24, wherein said at least one centralizing blade core is swept.
 27. The method of making a combined casing coupling and a casing centralizer of claim 24, wherein said at least one centralizing blade core is helical.
 28. The method of making a combined casing coupling and a casing centralizer of claim 23, further comprising the step of: post weld heat treating said at least one centralizing blade cores prior to hard facing said outward facing surface.
 29. The method of making a combined casing coupling and casing centralizer of claim 28, wherein said hard facing of said outward facing surface forms a hard faced surface along the length of said outward facing surface of an arcuately shaped transverse cross section.
 30. The method of making a combined casing coupling and a casing centralizer of claim 29, wherein four centralizing blade cores are attached to said casing coupling.
 31. The method of making a combined casing coupling and a casing centralizer of claim 29, wherein said at least one centralizing blade core is swept.
 32. The method of making a combined casing coupling and a casing centralizer of claim 29, wherein said at least one centralizing blade core is helical. 